Usually in an X-ray device like a CT (computer tomograph), a voltage from an electrical grid is transformed in a high voltage that is supplied to an X-ray tube. The high voltage generator may comprise an inverter in which IGBTs or MOSFETs are used as switching elements.
Also in other medical imaging devices like MRTs (magnet resonant tomographs) a similar inverter may be used for generating the supply current of the coils generating the magnetic field for measurements.
In such an inverter the short circuit or over-current detection may be realized by monitoring the voltage across the switching element. The voltage across the switching element may be a good indicator of the current flowing through the switching element, since as a rule, as higher the current as higher the voltage across the switching element.
In medical imaging devices, in particular for reducing the weight of movable components (for example a gantry or arm with a detector), the inverters may be operated with a high frequency (up to 100 kHz or higher), since the weight of components like transformers and inductors may be reduced with raising frequency. Also full resonant high frequency modes are used, in which a resonant load is coupled with the inverter for producing a more sinusoidal output current.